def main():
    try:
        with open('test.txt','r',encoding='utf-8') as f:
            print(f.read())
    except FileNotFoundError:
        print('无法打开指定的文件！')
    except LookupError:
        print('指定了未知的编码!')
    except UnicodeDecodeError:
        print('读取文件时解码错误!')

if __name__=='__main__':
    main()